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Macster, by the 2002 MY they should have all had the new flange/seal on the IMSB right?
Our 01 never had its flange replaced, but it was a triple rib on a dual row bearing.
Maybe. Maybe not.
According to some reliable sources what parts were used is not consistent. Some engines could have ended up with the older style end flange seal.
FWIW, My "2002" Boxster was built in late 2001 and I believe has the single row bearing based on the end flange but even that is not a given. As one reliable source says, in so many words, you can't really know what's there until you look.
There is also the the possibility the end flange is replaced as a preventative measure regardless of whether it has the new seal or the old seal.
My car was in for a RMS leak under warranty. From Porsche's point of view the extra part and labor cost of replacing the end flange even if it may not be leaking and even if it is of the newer style is preferrable to even greater extra part and labor cost of having to drop the transmission again and replace the IMS end flange and bolts should the owner bring the car back with an "RMS" leak. The new RMS of course could be leaking so a good 2nd repair (if anything was learned from the 1st not so good repair) would replace this as well.
Far and away then the best course of action would be when the car is in for a RMS leak both the RMS and the IMS end flange and bolts are or should be replaced regardless if the end flange is the old style or new style.
Does Macster have the highest mileage Boxter on the forums at 307K miles?? Impressive.
During my trips around the western half of the country I've encountered reports of other high mileage (~300K or more) Boxsters. One report I recall has the car in the southern MO area and is reportedly a 2.5l car with its original clutch. The Springfield MO Porsche dealer SM told me of this car when I was there back in Jan. 2015.
The rear main “seal” is not the problem causing the leaks. The problem is the crankshaft design and consequently the lack of bearing support, chain drive forces, and the weight of the OEM flywheel causing the RMS to leak.
Once the crankshaft is checked to assure it is not out of round, you should consider getting the permanent RMS upgrade available at Vertex. They have created the bearing support that eliminates future RMS leaks and reinforces crankshaft support. I had them install this in my 1999 996 and am thrilled. The engine feels more solid and sounds (better) different.
The rear main “seal” is not the problem causing the leaks. The problem is the crankshaft design and consequently the lack of bearing support, chain drive forces, and the weight of the OEM flywheel (do you mean an unbalanced/worn DMF??)causing the RMS to leak.
Once the crankshaft is checked to assure it is not out of round, you should consider getting the permanent RMS upgrade available at Vertex. They have created the bearing support that eliminates future RMS leaks and reinforces crankshaft support. I had them install this in my 1999 996 and am thrilled. The engine feels more solid and sounds (better) different.
Balanced or unbalanced DMF impact the crankshaft, it's the weight.
I contacted Gilbert at Vertex and he stated that since the product is new they haven't uploaded the information to their website. Being the Holidays he did not give a definitive date about publishing the information at their website.
Interesting idea .If it is necessary, surprising that LN,Jake Raby, Hartech and others never have mentioned developing such a product.
There have been other Threads where there has been comment on the huge amount of weight that the rearmost bearing supports because the DMF+clutch assy.weighs 50 pounds. So it is all the more surprising that an upgrade was not developed - until now.
At 30pounds, an unbalanced DMF (and many are unbalanced) is a problem that is easily & inexpensively rectified during a rebuild & when fitting this new , reinforced bearing carrier.
The other problem is that the DMF is huge heat sink/source for that bearing and the gearbox.
No reason for this "product". Its a band aid for a machining issue from the factory. There's plenty of bearing support. The crank carrier is held in place by two 11mm dowel pins, and also all 24 cylinder head bolts, which thread into it, providing clamping load. It takes more than a 50 pound flywheel assembly to create a problem with this. That as BS created by marketing from those trying to sell a junk lightweight flywheel 15 years ago. The cases where the RMS issues exist were factory mis- machined.
I spend my time developing things that are really necessary.
The RMS Fix does not address any issues related to the crank carrier. Instead it directly resolves the crank shaft design problem; the last bearing and the load forces present. Specifically the root cause of the issue with the RMS leak, a design flaw which comes from a combination of a heavy flywheel, the length or load point from the fulcrum lever of the last bearing, the chain (which is placed on this end, unlike the air-cooled crank chain), and the small bearing surface area of bearing number 7.
The OEM DM flywheel is heavy and the distance of this 30lb mass from bearing cause excessive rotational radial forces along with the additional load from the IMS chain cause excessive forces on the crankshaft. This combination of design and forces cause premature wear on bearing 7, and under extreme conditions failure.
Take a look at the pictures below. The picture on the top shows the bearings found in the M96 (left) and the bearings found in the air-cooled (right). In addition to the size difference there are twice as many lubrication ports. The next picture shows the end of the crankshaft for both the air and M96 engines. With the bearings in place, you’ll see chain gears and the crankshaft end at flywheel. The bearing of the air-cooled sits near the edge of the crankshaft, while the M96 has chain gears beyond the bearing or fulcrum point. Check out the difference in size between the bearings. The air cooled has 30mm of surface area to handle the loads while the M96 bearing has 12mm of surface area. That’s 2 ½ times smaller surface area to handle an even greater load capacity difference! Imagine the forces on that small bearing, the forces from the IMS chain, and the forces from the flywheel.
The first symptom is a vibration to the crank which causes improper sealing of the rear main seal. When the problem gets more severe, there is a twisting or bending of the last crank journal which then provokes the lubrication failure to the last journal and consequently the lack of lubrication to cylinder number 6 rod bearing which is lubricated via the last main bearing number 7. When bearing number 7 is expanded or out of tolerance due to the vibration and twisting of the crankshaft, then the oil pressure will not reach the number 6 rod journal and ultimately fail.
The vibration and twisting of the crankshaft on the last bearing causes main bearing number 7 to expand and wear out, or lose its tolerance and then fail to lubricate rod number 6. This problem is caused by the fulcrum distance, the heavy flywheel the additional chain load and the small bearing surface area. The loads that are present are greater than what the last bearing is capable of carrying and theses forces cause premature failure.
Check out the picture below that shows the RMS Fix as an additional bearing “Number 8” at the proper point to eliminate the fulcrum lever and increase the last bearing’s surface area to provide proper support. The unsupported excessive weight at the end of the crankshaft is now supported by this new Number 8 bearing with the old bearing.
This new Number 8 bearing consequently eliminates rear main bearing seal oil leaks, reduces engine vibration, increases the life of bearing number 7, eliminates the risk of rod bearing number 6 failure from lack of lubrication and most important reduces the consumers’ running costs for maintenance and total engine failure. We are working on adding this information to our website, if you would like even more details, please contact Vertex.
These two cannot be compared. The statement that was made failed to note the differences in crankshaft deign between the two engines. The aircooled engine uses the rear main not only for radial support of the crankshaft; but, also for longitudinal crankshaft support. The M96 does not do this, as it adjusts longitudinal end play, and carries those thrust loads at the center main position of the crankshaft. This changes everything. With thrust control being handled by the center main, via a pair of thrust shims, the task of longitudinal thrust control is removed from the rear main bearing altogether. These are the details that people need to understand concerning the design differences between the two engines, and why this comparison is like comparing apples to grapefruits.
The reason these engines lose #6 main bearings (on track) comes from heat saturated through the clutch, that is transmitted through the flywheel (another reason an aluminum flywheel is a bad idea) and then into the crankshaft, impacting the rear main bearing. This creates oil shear, leading to wear- metal generation, which then floods the #6 rod bearing with debris laden, centrifugally delivered oil, which then takes out the #6 main bearing.
If indeed the new "number 8 main bearing" is intended to carry load, how is this unit lubricated with oil from the primary oil system?
Last edited by Flat6 Innovations; 12-28-2016 at 12:45 PM.
Rod,
Details make the Engineer.
Your post reads:
"the M96 (left) and the bearings found in the air-cooled (right). "
Actually ,the opposite is what you mean ?If so, suggest you fix it
I am encouraging you because anything that improves the M96 is welcome. Your explanation is plausible . Suggest you need to work on the rest of the story.
1. If the larger bearing solves the problem, you have test results for that right ?
2. These results would show a substantial reduction in flex and vibration at different sustained engine speeds on a test rig.
3.The same test results would show a reduction in heat in the proximity of the new bearing also.
4.You have comparitive data from 2 identical engines with balanced DMF- 1 with the new bearing ,the other with the stock bearing ??
Without such test results your product is merely an intriguing diy project.I agree ,it would probably do no harm but let's try a more ambitious goal than that? Test data would quickly neutralize most of the dismissive comments from us. All that would remain to validate your product would be long term field/race testing.
Without the rigor of debate and testing this is interesting idea is doomed - like grooved oil pump drive shafts and DOF. Let's avoid that?
I hope you can continue to develop this idea successfully.We need every upgrade we can get for the M96.
Rod,
Details make the Engineer.
Your post reads:
"the M96 (left) and the bearings found in the air-cooled (right). "
Actually ,the opposite is what you mean ?If so, suggest you fix it
I am encouraging you because anything that improves the M96 is welcome. Your explanation is plausible . Suggest you need to work on the rest of the story.
1. If the larger bearing solves the problem, you have test results for that right ?
2. These results would show a substantial reduction in flex and vibration at different sustained engine speeds on a test rig.
3.The same test results would show a reduction in heat in the proximity of the new bearing also.
4.You have comparitive data from 2 identical engines with balanced DMF- 1 with the new bearing ,the other with the stock bearing ??
Without such test results your product is merely an intriguing diy project. Test data would quickly neutralize most of the dismissive comments from us. All that would remain to validate your product would be long term field/race testing.
Without the rigor of debate and testing this is interesting idea is doomed - like grooved oil pump drive shafts and DOF. Let's avoid that?
I hope you can continue to develop this idea successfully.We need every upgrade we can get for the M96.
At minimum. Don't forget UOA before and after to see how that added material effects wear metal levels. Or material type, you can't just expect some scrap piece of 6061 to handle this load, (as a random example) and I'd expect a lot of the same issues with material choice as what I went through for several years with the IMS Solution development. When adding a wear surface, friction can (and most of the times does) increase, so this should be indicative in UOA very clearly.
In this region of the engine there's no primary oil pressure delivery, only splash oiling, hence my question about how a supply of fresh oil is supplied to the new bearing, to both cool, and lubricate it. I am always trying to make the machine simpler, by removing parts, and wear surfaces, so hopefully Rod can shed some light on this.
12-23-2016 | 11:46 AM
